One second please

I'll be in the middle of doing something with Luke or talking to him and all the sudden he'll get this serious look on his face and hold up a finger to me like he's saying "one second please", then he'll run off somewhere to do whatever it is that is that suddenly popped into his little head at the moment that is so pressing. He is very serious when he does this and I know that whatever he is off to do must be pretty important because he doesn't do it very often.